The Wi-Fi icon says connected, yet a page will not open. In Nigeria, that can mean several different things: the laptop may have joined the router, while the router has lost its mobile or fixed internet connection. Start by checking the path between the laptop and the internet instead of changing settings at random.
Check another device first
Try opening a page on a phone connected to the same Wi-Fi. If the phone also fails, the problem is probably beyond the laptop: check whether the router is powered, whether its internet indicator has changed, and whether your mobile data or subscription is still active. If only the laptop has trouble, keep investigating that device.
Separate Wi-Fi from internet
A laptop connected to a phone hotspot can still have no internet if the phone has weak mobile signal, has run out of data, or has mobile data switched off. Check the phone itself by opening a page with Wi-Fi turned off. If that works, reconnect the laptop to the hotspot; if it does not, move the phone to a spot with better reception before changing laptop settings.
Make one change at a time
If other devices browse normally, disconnect and reconnect the laptop’s Wi-Fi, then try a different website or browser. Restarting the laptop can clear a temporary connection problem, while restarting a router may help if it has stopped responding; avoid resetting it to factory settings unless you know how to restore its setup. Note which step fixes the issue so you have a useful clue if it returns.